Capacitive sensors can be used for distance measurement and position detection. Various arrangements of the electrodes of such sensors create an electric field between the electrodes. As the electric field changes, a corresponding current change can be measured, and the parameters of a coupling network between the electrodes can be determined from the relationship between current and voltage.
An object that is brought or moves into the field between the electrodes can alter the properties of the field in a variety of ways. For example, the object can increase the coupling by coupling via a higher permittivity. The object can also increase the coupling by electrical conductance. Additionally, the object can decrease the coupling by causing a surge of part of the field to ground.
Using multiple electrodes, a kind of electrical tomography of the space in front of the electrodes can be produced. This sensing principle is currently well-known for the realization of seat occupant sensors for the front passenger seat of a vehicle. Additional sensing and measurement challenges in automobiles and other applications may also be met by capacitive sensors, which can be less complex and therefore less expensive than other technologies while also providing technological advantages.